Valve wear in heavy duty methanegas fueled engines : A study of the influencing factors for valve designs

Sammanfattning

The transition to a sustainable transportation has increased the demand for alternative fuel engines, such as heavy-duty methane-fueled Otto engines. This thesis investigates valve wear mechanisms in such engines, focusing on the impact of material properties, valve geometry, and operating conditions. Unlike in diesel engines, lacks Otto gas engines the lubrication which comes from fuel additives in diesel. Together with higher exhaust temperatures and reduced tribofilm formation leads this to increased wear. Through a combination of finite element method (FEM) simulations and experimental engine testing, the study evaluates intake and exhaust valves performance and wear in SCANIA methane engines. Simulation results indicate that while intake valves generally meet SCANIA safety factor (SF) requirements, exhaust valves often fall short. Experimental analysis reveals wear patterns such as micropitting, abrasive wear, and tribofilm delamination, with significant cylinder-to-cylinder variation. The findings suggest that optimizing valve geometry, especially for exhaust valves, and improving tribological conditions are critical for enhancing durability. Recommendations include further simulation refinement, prototype testing, and expanded field studies to validate design improvements and reduce maintenance needs in methane-fueled heavy-duty engines.